This invention relates to a color diffusion transfer photographic element. Particularly, the invention is concerned with a color diffusion transfer photographic element comprising a novel color image forming material.
As for a color diffusion transfer process by use of a color diffusion transfer photographic element, there are various methods depending on the manner in which a color image forming material releases diffusible dyes when developing silver halide. A typical example of a first type method is the so-called dye developer method wherein a dye developer is a compound having both a dye moiety and a silver halide developing moiety in one molecule and the dye developer as a color image forming material is oxidized with silver halide so as to change its diffusibility.
This type method for a color diffusion transfer process is disclosed in many patents such as British Pat. No. 804,971.
In the above-mentioned dye developer method, a dye developer generally in an unexposed area after imagewise exposure of a photographic element is diffusion-transferred to an image receiving layer and the transferred dye developer still has a silver halide developing moiety which is quite reactive. Consequently, it adversely affects on the dye image obtained which image suffers from color stain or change in color tone due to air oxidation or the like reaction since the transferred dye developer is reactive as mentioned above.
A typical example of a second type method is the method using, as a color image forming material, a silver halide color developer which is oxidized by silver halide and subjected to a coupling reaction with a nondiffusible color image forming material and, further in some cases, subjected to a ring closure reaction to release diffusible dyes.
This type method for a color diffusion transfer process is disclosed, for example, in U.S. Pat. Nos. 3,227,550, 3,443,940 and 3,227,551, and British Patent 904,365.
In the above-mentioned second type method, it is essential to use a silver halide color developer which usually is a p-phenylenediamine type compound.
In many cases, the above-mentioned p-phenylenediamine type compound gives unfavorable effects to dye images because its oxidation product generally causes serious color stains. Further, said p-phenylenediamine type compound has a tendency to cause dermatitis on the skin of users in practical use.
In addition to the above-mentioned two type methods, there is a third type method, of which typical example uses nondiffusible color image forming materials either directly oxidized by silver halide or subjected to an oxidation-reduction reaction with a silver halide developer oxidized by silver halide for causing a ring closure reaction or alkaline hydrolysis to release diffusible dyes or their precursors. (These materials are the so-called dye releasing redox compounds and hereafter they are called as the DRR compound.)
This type method for a color diffusion transfer process is disclosed, for example, in U.S. Pat. Nos. 3,698,897, 3,725,062, 3,728,113, 3,245,789, 3,443,939 and 3,705,035, Japanese Laid-Open-to-Public Patent Publication Nos. 33,826/73, 118,723/75, 2,327/72 and 64,436/74, and Japanese Pat. Publication No. 39,165/73.
The above-mentioned third type method is advantageous, in comparison with the foregoing two type methods, in that what is transferred to an image receiving layer comprises only a dye moiety or a dye precursor moiety without any developing moiety as well as in that it is not essential to use a color developing agent such as p-phenylenediamine type compounds but possible to use a black-and-white silver halide developing agent and therefore dye images with reduced color stain may be obtained therein.
In the above-mentioned third type method; that is, the so-called DRR method, a photographic element containing a light sensitive silver halide emulsion layer and a nondiffusible color image forming material; that is, the DRR compound, is exposed to the irradiation to form a latent image in light sensitive silver halide, and then, if desired, treated with an alkaline processing solution in the presence of a silver halide developing agent. At the time of the treatment with the alkaline processing solution, the above-mentioned photographic element and the image receiving element are superposed on each other and, as the result of the treatment, diffusible dyes released from the nondiffusible DRR compounds are transferred by diffusion to the image receiving layer, thereby to form dye images thereon.
The suitable compound used in the above-mentioned DRR method has to meet the following essential requirements:
(a) that it should be sufficiently stable before and after the processing; PA1 (b) that it should react rapidly in an exposed area and should rapidly release diffusible dyes or their precursors at the time of processing; and PA1 (c) that it is sufficiently stable in an unexposed area even at the time of processing.
As the DRR compound used in the DRR method, there are known heretofore various compounds as disclosed in the above-mentioned patents.
It cannot be said, however, that any of the conventionally known DRR compounds satisfy all the above requirements of (a) to (c).
Thus, the object of the present invention lies in providing a novel color diffusion transfer photographic element comprising a novel color image forming material. Particularly, this invention resides in providing a novel color diffusion transfer photographic element suitable for a DRR method using a novel DRR compound. In other words, the object of the invention is more preferably to provide a novel color diffusion transfer photographic element for a DRR method using a novel DRR compound fully satisfying all the above-mentioned requirements of (a) to (c) which the DRR compound should meet. The still other object of the invention is to provide a new color diffusion transfer process according to a DRR method using a novel DRR compound which is sufficiently stable not only in case of the incorporation into an photographic element for the color diffusion transfer method but also in case of the preservation over a long period of time, and shows such a rapid reaction at the time of the exposure to the irradiation and of the subsequent treatment with an alkaline processing solution as to release diffusible dyes or their precursors.
Another object of this invention lies in preparing a color diffusion transfer image having little color stain but a clear and stable color tone within a shorter time according to said color diffusion transfer process.